Underground Thermal Properties Analysis for Ground Source Heat Pump Application

Three adjacent boreholes were drilled in Chongqing of China. One was for underground temperature monitoring; the other two were for thermal response test (TRT). The underground temperature measurement results show that, in the borehole region, the variational ground temperature zone is from 0m to 10m and the constant temperature zone is below 11m depth. The geothermal gradient is various in different lithology zones. The TRT results show that the average ground thermal conductivity of the borehole region for single-U and Double-U configurations are almost the same, while borehole thermal resistances for the two configurations vary greatly.